1. Field of the Invention
The present invention relates to a fume hood apparatus, and in particular to a fume hood apparatus with an alarm system that monitor the fume hood""s key system components and provides an audible and/or visual indication of a set-up, normal or abnormal condition.
2. Description of the Related Art
Fume hoods are protective enclosures that provide ventilated and illuminated workspaces for laboratory or other applications. A fume hood in its most basic form is a box with an inlet and an outlet. The inlet generally has a movable sash (vertically, horizontally or a combination of both), which provides an opening that allows access to the workspace. The procedures performed inside the fume hood are exhausted at the back through the top of the fume hood to a heating, venting and air conditioning (HVAC) system.
For safety considerations, it is desirable that the technician be provided with information relating to one or more working conditions of the fume hood. The inventors of the present invention have recognized this problem and have developed a fume hood with an alarm system that provides a visual and/or audible indication of one or more fume hood working conditions.
The present invention comprises a fume hood apparatus including an enclosure, a movable sash and an optional air chamber. The optional air chamber includes an inlet for drawing air into the air chamber. Initially, the airflow travels upward into the air chamber. A backpressure redirects the airflow to travel downward through one or more baffles that evenly distribute the airflow within the air chamber as the airflow travels through the air chamber. A discharge positioned proximate to the face of the fume hood directs an unimpeded flow of air through the face of the fume hood. When the air moves into the fume hood around the technician""s body, an air turbulence may be created between the technician""s body and face of the fume hood in the breathing zone. By directing an unimpeded flow of air downward across the breathing zone of the technician, the air from the air chamber reduces the forward momentum of air trying to escape the fume hood, thereby reducing airborne contaminants from escaping through the face of the fume hood. Further, airborne contaminants are reduced from escaping from the workspace even when the movable sash is fully opened resulting in improved containment performance.
In one embodiment of the invention, the fume hood also includes an alarm system for providing a visual and/or audible indication of one or more working conditions of the fume hood. In this embodiment, the alarm system includes an air flow sensor preferably located in the air chamber for measuring air flow characteristics, such as velocity, air flow rate, or the like, and a sash position sensor for determining the position of the movable sash with respect to a predetermined height above the bottom of the sash opening. The alarm system also includes a controller for processing the signals from the air flow sensor and the sash position sensor and for providing a signal to one of the visual and audible indicators depending on the characteristics of air flow and the position of the movable sash.
Various aspects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.